Monday, May 25, 2015

FT-707 repair (4) 10m B crystal

Here's a fix for those who own a FT-707 converted to CB and need to revert back but don't have the original crystals (should work also on the FT-902 and others sharing similar design).

I just request the price, from an Yaesu distributor, for the original 10m band crystals (A,B,C and D). Price quoted was 18 Eur each. Well that's not in my budged since I will need 8 crystals (4 on each set) and that would give the wonderfull sum of  144 Eur, I almost can buy a radio for that money! Guess will have to wait for someone to sell a complete board from a scavenged unit, I've seen premix oscillator boards selling, on online auction sites, for half the price and with all the crystals there.

Anyhow I'm not to be stooped by this, after some calculation I beted that an crystal around 14Mhz will do the overtone job....bought a 14.318 Mhz unit by a woping 0.28 Eur (that's 28 cents) and replaced the crystal, on the 10m D band place, just for testing since I don't have the oscillator coil on 10mB, and this was the result:

I works, spans reception from 28.436 to 29.004 Mhz with the oscillator at 42.972Mhz (14.324Mhz) ! Perfect! Adjusting the premix oscillator variable coil was needed since it was set to the previous CB frequency.

So, for the 10m B position, i'm sorted, now I need to find the other 10m band crystals,  I was looking before on old crystalized scanners crystals and also model control ones, so far no luck on the exact frequencies. There are some specialized sites selling the needed crystal's at around 10 Eur each, still think it's too much for a piece of rock...

If by any chance you know where to find the following crystal's (cheaply) just let me know, apreciate:

The red cross one is the 14.318Mhz one tested. These 14.318Mhz crystals are also found on computer motherboards if cheaper, than 0.28Eur, source is needed!

Have a nice week!

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